How to assemble ? Requires 4 short M4 screws and nuts. To complete the wheel : Print the model 2 times, You may need a file tool (the thing you can remove plastic with, sorry I'm not sure about this tralation) to make sure the servo horn fits perfectly (it needs to be tight for it to trafer torque), Press the two parts together and put the screws. How to use ? When correctly assembled, the wheel provides 4 pai small holes to attach strings. The bigger holes make it easier to turn the servomotor. Why ? This was created in the context the BA2 project at EPB (ULB). Note : To anyone with the intention of using this model for the same purpose, don't forget to comply with the CC licee ! See also ... FS90 servo motor holder